This invention relates to shot or sand blasting machines for use in shot or sand blasting material in the form of wire or rod, the machine being of the kind comprising two centrifuge wheels in a closed housing which has an inlet for blasting shot or sand, means for conducting the wire or rod material to be blasted through the housing between the centrifuge wheels, and an outlet for scale blasted from the wire or rod material.
In one such machine the two centrifuge wheels are driven in opposite directions from each other, so that the blasting shot or sand from one centrifuge wheel impinges upon the blasting shot or sand from the other centrifuge wheel approximately in the region in which the wire or rod material is blasted. As a result the energy transmitted by the centrifuge wheels to the blasting shot is continually destroyed. This means that this energy must be repeatably renewed. Furthermore, the blasting shot or sand itself is subject to comparatively high wear. The blasting shot flung out from the centrifuge wheels collects at the bottom of the housing and is conveyed upwards again by an externally situated conveyor and is fed back again to the inlet regions of the centrifuge wheels. Along this transportation route of the shot or sand, scale or other material abraded from the rod or wire is separated from the shot or sand. This arrangement is disclosed in French Patent Specification No. 1,268,599.
A shot blasting machine is also known, in which three centrifuge wheels are arranged in a star pattern staggered from one another around the path of the material to be blasted in the direction of movement of this material. With each centrifuge wheel there is associated a guide device consisting of two adjustable guide plates. The guide devices feed the blasting material issuing from the centrifuge wheels against the material to be blasted. The shot or other blasting material here again collects in the lower region of the housing and must be supplied thence to the centrifuge wheels by separate conveyors. This machine is described in German Specification No. 1,815,187.
The main object of the present invention is to provide a shot blasting machine of the kind initially described which can be operated with a lower energy consumption, which is constructed as compactly as possible, and in which minimum wear of the blasting shot or other blasting material takes place.